The proposed research is a longitudinal study of long term marijuana use and consequences of use in a sample of 950 adults with a very high percentage of users (88% with some use after age 17); and who have spent at least one year during late adolescence to early adulthood as members of one of 60 communal living groups. The study builds on an existing data base of individuals first studied during the years 1974-76. Mean age was 25; 82% were from 1946-1959 birth cohorts. The sample is of great strategic interest because of: 1) the high proportion of regular marijuana users continuing the practice through their late 20s and 30s; 2) the numbers of transitions from use to nonuse that subjects have experienced (some going through as many as 3 complete cycles of stopping and starting again); and 3) the availability of data not only about individual dispositions and behaviors but also group level measures of social norms and organizational attributes of the communal peer networks. Each commune held clear beliefs about marijuana and other drugs and enforced group norms which actively encouraged, permitted but did not encourage, or renounced and prohibited drug consumption. We will take advantage of the unique opportunity thus afforded to classify our sample by communal peer group, which will enable us, in a quasi-experimental manner, to assess the relative causal influence of family of origin influences, youth peer group influences, life stage influences and intrapsychic influences as they impact upon drug attitudes and behaviors, and the consequences of different use patterns, during the transition from early to mid-adulthood. A subset of 183 subjects have been interviewed at three time points between 1974 and 1984; these cases will provide a multiwave subpanel of the larger two-wave panel study. The aims of our research are 1) to describe the marijuana use patterns through the life course of our subjects; 2) to analyze the antecedent and concurrent factors influencing the evolution, maintenance and change of drug behaviors; 3) to analyze the consequences for physical health of sustained marijuana use; 4) to analyze the psychological consequences of sustained marijuana use; 5) to analyze the social consequences of drug involvement especially as it affects conformity to the social roles of adult life. Our final aim is 6) to collect baseline data on the children of longterm marijuana users for a future study of the effects on children of marijuana smoking parents.